Lichens are consortiums consisting of some kinds of fungi and algae and belong to a group of plants which occupy a botanically specific position. Metabolites of these lichens, that is, lichen components are quite different from components of other various higher or lower plants and they belong to a botanically specific class. They are definitely classified by Asahina et al. [see Asahina and Shibata, "Chemistry of Lichen Components", published by Kawade Shobo, 1948].
It has been considered that a physiological significance of lichen components exists in defense against attack of microorganisms or insect plague because lichens grow slowly, or it exists in defense against ultraviolet ray because they grow in the sunshine, different from other fungi. Therefore, lichen components have hitherto been used for applications which came out of these functions. Examples thereof include dyes, antibiotics, falvors and the like. However, in fact, little study has been made on a pharmacological effect of these lichen components.
Lichens grow slowly and, further, their growth is liable to be restricted by natural environments (e.g. season, climate, temperature, latitude, etc.) as well as artificial environments (e.g. sulphur dioxide gas concentration, smoke concentration, etc.). Therefore, it is extremely difficult to culture lichens, which results in no success. Further, as is often the case in lichens, there the two are similar in form, but totally different in component. Therefore, selection of raw materials requires great skill and it is difficult to collect from nature. In order to obtain a method for producing lichen components, a study on cell culture has recently been made. Since lichens grow rapidly by cell culture in comparison with natural culture which needs a growth period of years or months. Therefore, it is possible to produce a subjective component in a short period of time. Further, different from a natural culture, there are advantages that is is influenced by the weather and need not a lot of persons on collection and, further, it is possible to conduct planned production on a industrial scale. As a method comprising for culturing lichen cells to be extracted and collecting a lichen component from the cells, for example, there is the present inventor's application (Japanese Patent Application No. 58-56689), however, superoxide elimination action is not described.
It is known that active oxygen species (e.g. superoxide, hydroxy radical, singlet oxygen, etc.) act as an important protection factor in a living body. For example, when virus or foreign body invades a living body, phagocytes (e.g. neutrophil, monocyte, macrophage, etc.) is activated to express a dynamic function such as migration ability, phagocytosis and the like, whereby, lysosome enzyme or superoxide is produced and discharged. These are directly or indirectly concerned with fusion and sterilization of ingesta to protect a body from a foreign enemy.
On the other hand, active oxygen species cause various tissue disorder if they are present in an excessive amount in a living body. The amount of superoxide which is considered to be the representative of active oxygen species produced in a body is about 1% or less based on the amount of oxygen absorbed by respiration, and superoxide is gradually eliminated by catalysis of superoxide dismutase (SOD) contained in cells. However, when an oxygen action is deteriorated as is observed in a body of the old, elimination is not completely conducted and, therefore, a concentration of superoxide becomes high, which results in tissue disorder (e.g. articular rheumatism, etc.) as well as cardiac infarction, cerebral hemorrhage, cataract, blotch and ephelis which are caused by superoxide or lipoperoxide produced thereform.
A skin is an organ wherein superoxide is particularly liable to be formed because it is directly subjected to stimulation of environmental factors (e.g. ultraviolet ray, etc.). Therefore, increase of the superoxide concentration and formation of lipoperoxide are liable to be arisen, whereby, disorders (e.g. formation of melanin pigment, blotch, fine wrinkle, etc.) are liable to be arisen.
Superoxide dismutase (SOD) is an enzyme having an ability to eliminate superoxide in a living body, but a half-time in the living body is short (within 5 minutes) and it is inferior in safety.